If you don't mind using unjacketed bullets, you can buy lead ones ready to go
https://itlshootingsupplies.co.uk/pr...t-heads/page/3
Come to around 8p each.
ITL sell jacketed ones too - more expensive of course.
https://itlshootingsupplies.co.uk/pr...t-heads/page/2
He is usually at Kempton, but do check with him.